Question Regarding the "Escape Test" on Gollum

By xBeakeRx, in The Lord of the Rings: The Card Game

So I just finished up my first attempt at The Dead Marshes (a victory - 93 points), but had a question regarding the Escape Test forced action on Gollum. The text of the card reads "At the end of the quest phase, the party must make an escape test..."

Now, my question arose when I had a Sneak Attack and Gandalf in my hand. I wasn't sure whether I could play my Sneak Attack during the quest phase and use Gandalf for the escape test, or if the escape test was, in essence, its own "phase" that I needed to wait for in order to play my Sneak Attack/Gandalf for. Another reason that I got a little confused was, in the rules supplement it reads, "After commiting characters to the test, the players may take actions or play event cards." This makes it seem like the escape test is it's own "phase", independent of the phases, and that I would need to wait to play my Sneak Attack for the escape test, rather than playing it during the quest phase.

What are your thoughts/opinions?